Time for multimedia SoCs to get their analog signals right

Manuel Mota, Synopsys
EDN (March 04, 2015)

Multimedia applications such as Digital TVs (DTVs), Over the Top (OTT) devices, and Set-Top Boxes (STBs) rely on digital and analog interfaces to transmit & receive audio and video content. The integration of digital interfaces is well established and understood; however, the integration of analog interfaces has usually been implemented with discrete external components. Today, cost, power, and area reduction requirements are driving the integration of analog interfaces into multimedia system-on-chips (SoCs). Among other challenges, successful implementation of modern multimedia SoCs requires a good understanding of the most relevant characteristics of analog interfaces and how they can be integrated while ensuring the transmission quality of the analog audio/video signals.

Analog Interfaces for Multimedia SoCs

Today’s TV sets are bigger than ever, however there isn’t a lot of room available for more electronic systems beyond the large flat screen and connectors in the back. STBs are small and getting smaller – some are just an attachment (a “pen”) that connects to different sources of content through wireless, satellite and cable connections. Home broadband networks have effectively eliminated the need to store recorded content locally, relying instead on a central cloud storage that is streamed to the STB or DTV via wireless or wireline data connections. OTTs are Set-Top Boxes that do away with cable/satellite connections and simply rely on streaming content, typically via broadband WiFi.

A multimedia SoC needs different analog interfaces for the given application:

• Digital TV chips interface with: WiFi, TV tuner, analog audio outputs and inputs (such as loudspeakers, microphones for voice commands) and potentially a cable or wireline transceiver.
• Set-top box chips interface with: WiFi, TV tuner, analog audio outputs and inputs (such as loudspeakers), with cable and or satellite reception and potentially a cable or wireline interface. They typically include several analog video outputs.
• OTT chips interface with: WiFi, potentially with a cable or wireline interface. They typically include an analog video output.

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